HIV and sexually transmitted infections (STIs) disproportionately affect Black adolescents and young adults in the United States. Environmental or structural factors such as discrimination, crime, and poverty have been proposed as potential drivers of persistent racial disparities. Though HIV and STI incidence tend to be geospatially clustered, the specific environmental predictors of clustering among Black adolescents and young adults are not well understood. Exploratory mapping using geographic information systems (GIS) has revealed that HIV and STI incidence in adolescents and young adults is higher in certain neighborhoods in Massachusetts, the setting of the proposed project. Determining the associations between specific environmental factors in neighborhoods and HIV/STI incidence in Black adolescents and young adults is important for intervention planning. Candidate: My career goal is to become an independent investigator focused on developing structural interventions for HIV/STI prevention in underserved communities. As a physician trained in Infectious Diseases, I am fully committed to overcoming persistent health disparities noted among people at risk for and living with HIV and STIs. To become an independent investigator, I require additional research training and mentorship, building on the clinical, publc health, and implementation science training that I have previously received. Research Proposal: The primary objective of this proposal is to determine the relationships between neighborhood-level environmental factors and HIV/STI incidence in Black adolescents and young adults. The proposed study has three AIMs: (1) to qualitatively explore the impact that environmental factors have on HIV and STI risk behavior by conducting focus groups with Black adolescents and young adults from higher and lower HIV/STI incidence neighborhoods; (2) to quantitatively determine the association between selected environmental factors and HIV/STI incidence using geospatial analysis; and (3) to use a mixed- methods participatory approach to identify interventions to address environmental factors associated with HIV/STIs using data gathered in AIMs 1 and 2. Training: The research plan will be supported by courses in qualitative, quantitative, and geospatial analyses, clinical trial design and utilization of large scale socio-behavioral and demographic data sets for secondary analyses. Mentorship and Resources: My mentorship team will be co-led by Dr. Kenneth Mayer, Infectious Disease Specialist and expert in HIV/STI prevention and Dr. Laura Bogart, social psychologist with expertise in disparities in HIV, adolescent health, and qualitative and quantitative methods. To achieve my goals, I will avail myself of the resources available within the Division of Global Health Equity at Brigham and Women's Hospital, the Fenway Institute of Fenway Health (www.thefenwayinstitute.org), and the Harvard Center for AIDS Research. I will also benefit from a team of dedicated advisors in geospatial analysis, behavioral health and adolescent sexual health.